DAB radio

[X3nut]

This is a bit baffling but I've noticed that when I pull away and the doors auto lock the DAB drops it's signal for a few seconds then comes back. It's even done it when I apply the brakes and come to a stop but only when the car stops and not before....any ideas?

[sapphireblack]

Duff connection perhaps, but where? Hopefully not

[X5Sport]

Sounds a bit odd. Either you are in a very weak DAB signal area or there is a wiring fault with the antenna grounding. It almost sounds as if there’s a ‘spike’ generated on the car when a high current momentary load occurs (such as the activating of all the locks or applying the brakes).

What state is the battery in? What I’m thinking is something going bad in the battery or alternator circuits that causes a momentary voltage drop and this causes the radio to drop. What happens if you don’t start the car but tap the brakes or fire the locks? Does the DAB drop? BMW have systems that ‘shed’ load by turning accessories off (such as the radio system) if the voltage is a bit low.

I’ve chased vehicle faults such as this many years ago and the issue was usually damp, a bad switch or corroded earth in the vehicle (which means the device grounded via a different route than it was supposed to), or an issue with the battery.

[X3nut]

I'll try and look into it a bit more at the weekend but the battery is about 6 months old and has been coded to the car (according to Halfords anyway). I have the flickering interior centre light as well which could well be caused by a bad earth. Where could the grounding wires be?

[sapphireblack]

X5Sport will be better informed than me, but I'd be looking in the bowels of the boot for any signs of water ingress. Theres lots of electics located under the floor.

[X5Sport]

Ground wires are all brown (with no other colour in the wire) and they’re all over the place! Check the tightness of the earth at the battery itself and how good the connection is at the body end of the same cable. At least they’re easier to get to than the E53 was!

Definitely look for water around that area of the boot as suggested. It’s more of an issue on the E53, but not unknown on yours.

From what you are describing it sounds more and more as if something is electrically ‘floating’ rather than grounding correctly. There are earthing ‘combs’ all over these cars. The comb is just a metal connection device that lots of wires connect to and bolted to the chassis.

[sapphireblack]

Did this crop up after battery replacement?

[X3nut]

No the problem was there before as I had the low battery sign every time I got in it so had the battery replaced. Hasn't worked well though as the low battery warning still pops up but then again I only do about 50 mile a week at the weekends.

[X5Sport]

You might be wise getting a battery conditioner then. A number of us use CTEK MXS 5 and MXS 10 8-stage conditioners as we are also low mileage users. It could be the battery is slowly declining through lack of use. You’d be surprised as to how long it takes to put the starting charge back in again (20 miles or so). I charge the X6 monthly and the E46 is permanently connected over winter storage.